Glossary
@Override Annotation
An annotation used to indicate that a method in a subclass is intended to override a method in its superclass. It helps catch errors if the method signature doesn't match.
Example:
The @Override annotation above the toString() method in Assignment indicates that this method is providing its own implementation of a method inherited from a parent class.
Access Modifier
Keywords in Java that set the accessibility level for classes, variables, methods, and constructors. They control where a member can be accessed from.
Example:
Using private as an access modifier for correctAnswer in the Assignment class means it can only be accessed within that class.
Constructor
A special type of method used to initialize new objects of a class. It has the same name as the class and no return type.
Example:
public Student(int gradeLev, String fullName, int ageNum) is a constructor used to create and set up a new Student object.
Getter Method
A method that provides read-only access to an instance variable, typically returning its value. They are also known as accessor methods.
Example:
public int getGradeLevel() is a getter method that allows other parts of the program to retrieve the student's grade level without directly accessing the private variable.
Instance Variable
A variable declared within a class but outside any method, constructor, or block. Each object (instance) of the class has its own copy of these variables.
Example:
In the Student class, name and gradeLevel are instance variables because each student object will have its own unique name and grade level.
Javadoc Comments
Special multi-line comments in Java that begin with `/**` and end with `*/`. They are used to document code and can be processed by the Javadoc tool to generate API documentation.
Example:
The comment /** Represents an assignment that a student will complete */ above the Assignment class is a Javadoc comment, explaining its purpose.
Method Header
The first line of a method declaration, specifying its access modifier, return type, name, and parameters. It defines the method's signature.
Example:
public boolean gradeAssignment(boolean studentAnswer) is a method header that tells us the method is public, returns a boolean, is named gradeAssignment, and takes a boolean parameter.
Method Name
The identifier given to a method, used to call or invoke it. It should be descriptive of the method's purpose.
Example:
gradeAssignment is the method name for the function that checks if a student's answer is correct.
Mutable Object (as parameter)
An object whose state (its instance variables) can be changed after it is created. When a mutable object is passed as a parameter, changes to its internal state *will* affect the original object outside the method.
Example:
If a Student object (which is mutable) is passed to a method and that method calls student.setName("New Name"), the original Student object's name will be updated.
Parameters
Variables declared in the method header that receive values (arguments) passed into the method when it is called. They allow methods to operate on specific data.
Example:
In public boolean gradeAssignment(boolean studentAnswer), studentAnswer is a parameter that holds the student's submitted answer.
Pass-by-value
A mechanism where a copy of the actual argument's value is passed to the method parameter. For primitive types, changes to the parameter inside the method do not affect the original variable outside.
Example:
When you call calculateSum(int num), num receives a copy of the value, so if num is changed within calculateSum, the original variable remains unaffected.
Reference Variable
A variable that stores the memory address of an object, rather than the object's actual data. When a reference variable is passed to a method, a copy of this memory address is passed.
Example:
In Student myStudent = new Student(...), myStudent is a reference variable pointing to the Student object in memory.
Return Type
The data type of the value that a method sends back to the caller after its execution. If a method does not return any value, its return type is `void`.
Example:
In public int getGradeLevel(), int is the return type, indicating the method will send back an integer value.
Setter Method
A method that allows modification of an instance variable, typically taking a parameter to update the variable's value. They are also known as mutator methods.
Example:
public void setName(String fullName) is a setter method that allows the student's name to be changed from outside the class.
private (Access Modifier)
An access modifier that restricts access to a class, method, or variable only within the class where it is declared. It promotes encapsulation.
Example:
The name variable in the Student class is private, meaning it can only be directly accessed or modified by methods within the Student class itself.
protected (Access Modifier)
An access modifier that allows access to a member within its own class, classes in the same package, and subclasses (even if in different packages).
Example:
A protected method in a base class might be designed for use by its derived classes, but not by unrelated classes.
public (Access Modifier)
An access modifier that makes a class, method, or variable accessible from any other class. It provides the widest scope.
Example:
A public method like getGradeLevel() can be called by any other part of the program to retrieve a student's grade.
toString() Method
A method inherited from the `Object` class that provides a string representation of an object. It is often overridden to provide a meaningful description.
Example:
Calling System.out.println(myStudent) implicitly invokes the toString() method of the myStudent object to print its details.
void (Return Type)
A keyword used as a return type for methods that do not return any value. These methods perform actions but don't produce a result to be used by the caller.
Example:
The setName(String fullName) method has a void return type because its purpose is to change the student's name, not to provide a value back.